recover the oracle RMAN tablespace if it is dropped

Step 1:
Restore the control file that was taken before the tablespace was dropped

Step 2:
Restore and recover the db
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RMAN> run
2> {
3> set UNTIL TIME "to_date('YYYY-MM-DD HH24:MI:SS')";
4> restore database;
5> restore archivelog;
6> }
RMAN> recover database until cancel using backup controlfile;
RMAN> alter database open resetlogs;
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Check if the tablespace is visible after recovery of database :
select tablespace_name from dba_tablespaces where tablespace_name = '<table space name>';

After recovery is complete, you can try with this options
RMAN> alter tablespace <tablespacename> offline;
RMAN> restore tablespace <tablespacename>;
RMAN> recover tablespace  <tablespacename>;
RMAN> alter tablespace online;